SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e6decce4bfaa54d7199e48443816fbc4fcfb64096655ac3603ad21af74eea40' 
  AND token = 'j4RBxJNZCvbCifQCN8I34+jM/X3RRis64AxiCaUZqi0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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