SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50fe94a531b6d25d064873d64815762c853210b89242031014683be51cded803' 
  AND token = 'jaUkxy2MNE2k1VH5WD1hOeTcPXQdbmhF/zoPowchepY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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