SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ad2b94b625f271fbfc6253f7291890c781249b0adc01df1e2685a354ac1f813' 
  AND token = 'onVUcBEQIncVRS8zGcnFFbVx3UdA0ILBWtrgLRxzfbE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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