SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '342c76a208cd7cdde0ce97767439afb68ddee5b4247bf335105d8a4fb417568b' 
  AND token = '2axTKrKY5+QSomV5BHPSPpuDL2Eig4g4COJ0Jn3LFuk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}