SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bf3dcf9c2f8f4a8918a74a1b5791b23566b82ab2f2d84e28ba2ccad462930b15' 
  AND token = 'n4NNV9LT23oQQH1IlXEf5wJZpFKUUqUyVmr7kzrKvyY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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