SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7835b0333acb2cf98764befde41ef4604e978955caea3f0eba9e940ad1efb795' 
  AND token = '8G0HCWrnhb5dBPfvUcSQyTypuh3PfFS12HPDA1Px+j0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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