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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f0bce9e0a69f14eb96a0982ee6578e1ee86e7fbf02338ca15632a0b0cfd75e7d' 
  AND token = 'TkEB1Wkm9UUe7d4NlRSiTuZz7TN/+vPC44fykHQEoL4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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