SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '188eeba86e7cefb29bceae5c14cb9900ad0304504ccae816af1838fbe4ff9f91' 
  AND token = 'kQKQfh1rmuxmGXNuiKs8HBfJnV4mvWhN6Jbq4xPHrCA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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