SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff998168032fab9837b116b2301d353d876c5cda8e82dcc52aeba8bfe16cc06f' 
  AND token = 'DI5i/qMDT3Pz5rTLcL0kdR4tmGZGxntqDbJpkbgQr5c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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