SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3fe7fd45e20f8c2068aa21ef48318314c22af262eb1864f88e96335e0a17a0d3' 
  AND token = 'uU0NN2k9Q3csNaNKBsk8T2qjAdQBV+s0Tf3p6rmSwQQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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