SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3300db8dd4620e40f50b4572815070873eb2f827c6629af60f25e187daa8538a' 
  AND token = 'Gze1UX2JZEf2tANSICI6KMdUsjxe4qP6RgikjWse90g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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