SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '49d343116e662c83e001039dd28775167a6eca97712936c1902d673f4a2f94b7' 
  AND token = '2RMb7ILT1YZRPNFI0NOrtwTr0tnMNIVN312gJLmeQpk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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