SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0e2847320ef36c203099dbaa636521e427fede53472096bd2090424c941b5d44' 
  AND token = 'oB5aZGrZtTFA/5K7svr9jPXlPg9sXaSzafI409zFwYU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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