SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9f3630bcc115fd22f3fda7ebebfbd2ba5dd0248d920e12a41cb187d3ed9e337a' 
  AND token = 'nUckSpznBbmAHsYtkMJawtt/Xde5BSodT0u/EX1YcHo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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