SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b99a1cb9427e5104e4f95c319becd0fe0b5c9f5d98fa3fb3c4bd4547222bcc0' 
  AND token = 'ZRyFwOAsZG9fnp09YfW8EerOq+h+svlulPFMJe1Sy10=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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