SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2986e43ca8fb958655e7d027cf324076eae05f28227265bdcff3f37696aeda32' 
  AND token = 'bDXFK61YpFJL659BfIhRaSDVUla4zGvyBJWNhNJc1GQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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