SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cfcd051cb5979ee356fa2c188b661eccebc319efceb5ccd1660d3443bbf57c8d' 
  AND token = 'R0EJhz1vkMyMZ9AiFm+8BQ4zRLEWEwX7oxiR6Nv8rUk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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