SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a9fe0364766e7a935cb1201ef7a1008035aadff4855dd810bc412d6fde96ef6' 
  AND token = '8xadCIQALvp9bum63xaC6ISmxDSj2HnpgDsJSIc+7bc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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