SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '755f4aadf5114ac996e576a77f8f025995c0706a14eb31b95778e0936ca258c1' 
  AND token = 'S5+g/7Odra6xdhC7JaKw9ZaP6X+vqWuKdvzLZYGmtFw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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