SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f79460f7f5cc945254f62207a67d5b4b44737f69c5662e9466dc488d980de203' 
  AND token = 'FWT8ZQT6ng333LzRRGSTUWvkPCbrpyMPDDF+nCCZHKc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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