SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4481a1cb41710c088d4817a1d56b6fee8eccc301b1d63e63ddfb2bf3613c850' 
  AND token = 'HsC6s5Xa4FTpKJpgDzdPbFnfr/msx/JR9vzhhZz3j6M=' 
  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"
    }
  }
}