SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6b2be9a493726c934ba9b39c757c04f9dbbafa267e54c9bc93b706e5f6de620' 
  AND token = 'Dtw0/E4sGyX2N+sQ2KVtuIamOJPJgmg8vuDflqoQpBA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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