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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '5b65aa611147cea46f2ffd4394bcf36948ef9174cc854dcf188498a27e454b7c' 
  AND token = 'fzivMXCUWE8NGVN9XBBcPQtoVFdAd3z0PdW5BBRXiRA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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