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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6f47d65164f291c27656374593becee5ff52ed56b2ddf1d5e73b5018c5d75cf' 
  AND token = 'YD7MrEIE51KeSks3QpzDC91SEevVd68LTav3EeqksZM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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