SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd35777dd0b8d19719560d0a43792861e19497aefd806fd4063ca6f6ff01c6323' 
  AND token = 'isa76Ry2gBKJXCYkW0fUd7kQpQ5eyHfjeHuZWrfKadM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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