SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6588274aab5ae943c9733c4e3ee3d88e41bc2cf01195a964e4e94d946a693c5c' 
  AND token = 'jZKEzdJHvFptVVEbGGmTxk5umQ1ydUNFT7/UAFYGBXg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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