SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0390abf4cc76d0f9355f5388649e7d6f2d24a91021734f749a7d66e543655669' 
  AND token = 'EubsNqhIDQ4tuWUKskbfeoJ2+bcE/zzLemTQRYBYxi0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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