SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b56940d716bef8038f4a21abdf61a4b473fc032e47090b98723052af25190476' 
  AND token = 'zCbvFFjiA70KQVA9CulQMU1wMiG82d8Abx0OPWN1Fmk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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