SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c0b35c698708309530daf6ff17f289ea437017eb56fc1d2d1ea6f01728acc707' 
  AND token = 'WgQVuSfrUFyFgcWFvAAx2bxcfAQwfqGty/ofwQ84YDs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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