SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9fe4aec13c08234c98857cffebc86dbb23f882d406418863a640e9b3643decab' 
  AND token = 'FLkPvIF3OyM/tonHcDFYelblAM2hg4KZgnXe88SxIOM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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