SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b2a8c294c897087740486d6712c26d1a29280274484c074eed83f8bf957d9a7' 
  AND token = 'NsmJU/HMcyFsiGhKpEgQ5aY3FkClMrIT5BQqXuJhyrA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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