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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '7979dd56ea2ffc0aaba2fb6601c44ac3b37769d11d33971c6735576e603c7d50' 
  AND token = 'arI33y8+3h1mnkAlv/C3lRb1Fw6iIzuDKM6bkqGjd4I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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