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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '703b8127fda3e3c6fc9a6abdc5eae3e8e67f3cb67c2df5dd6ce88f3c10f2c36e' 
  AND token = 'MXc3WlEcH+QfQQE0lEz+pckRaXzdDQk9l6OnlyiDGC4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}