SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dcd59a83016940f048b81cc5d04cc8aab9d198b23736e4e9df8a9e787484e91f' 
  AND token = 'ORHcPQjvoFrDp2RuBDCCsFSC8Exz3xcwhhDSTs+MYSc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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