SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '678829252752a7a3fa896a47e80ee5ed1d193c376df4ab6f97b3bd2f18265af2' 
  AND token = 'gEnJXfQVyrN9KlrCDq70q8kHNXpwAF+/DMFFJdQviIc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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