SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52343d58d17bd48f1099caae8079769ae4c34681f65a69941a1959f05df0e46c' 
  AND token = 'SIDcxwD65mGE7SZvmlKolMyMAhKddQGrbuxybQH35pE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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