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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'ef1cafc88f08aa5945e903e14d14f2701d0abda4e286d7e3d25766232394b6a6' 
  AND token = '+1LSlUx0E3wKO7XyKE3jkLpgTNvR7r4HZEK9IlDSbno=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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