SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f4b243b9a6cf42d765632a38462b5ee0384cca1ffeee8628300cb0e331dbd7d4' 
  AND token = 'maybSVmEyiludzhYRFMWhZlZFXy1ffVkfonC16daLow=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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