SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '54d21d83f962062536cd3bd049a887064b7ddc1bcf2c5d2d417209aa5e049165' 
  AND token = 'YGkmsIYj+18EkwnSJCtC4jdTZZ1yvl/GChrvLhMk9fo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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