SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1290c8ccaee24853fe818a949f2fb6d96ac208d753e594457fe20fddc23168d' 
  AND token = 'b3Ny3GbSnXqFCfBO1LgxVchoP4Sg+xDDcH2zxkKxOl8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}