SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '840d69c9cd23388532677dbd9708df1afacae7e00233baef1ea7a56d1591cdf5' 
  AND token = 'b6iZtmmAIA8i+Nf0z8K4JQU4BVQGPF9NQAVhntStjsY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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