SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50dd2b181c239b4279f04600d057aa6ff1b5ddc66eed9df7677025c2d02efb3e' 
  AND token = 'IrP0ZwmID7ZEH33g0bmPgiOumRa/FR6awCZcMZL0CBE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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