SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '608d6f8d5d98e3e6e95a24d6579ada2065b2b73f0bc0fc3d99ed63138d839ef5' 
  AND token = 'QxhONP7KOREFLbKdQVD9V0mpi0Lnr88AMhE9wSdixzQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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