SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '59fbe756689ca215369f939f4a17cc5b38e7641a1e876798aade138d3cc3217f' 
  AND token = 'PwcaIF5mPGdPoWq6bWszhrs5P6fEAoNjbbrqBhysotA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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