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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'fe805218cfcc45ec039e9e96a4eb9355911021cafa6aba17e657b0d1bf2700de' 
  AND token = 'WhyIE7yaw5ddK6/ciDDFCFEn8lvd9czZu2Rrgwx+gjI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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