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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'dd3826e86f49ac25a9229e9f69e3ae71f8c65d508f0149d70d2a049076d29d35' 
  AND token = 'b10ukUtF2FRRMDoM6q6tMP3gdKo2QczEf4YhwUA/6ec=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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