SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aec0463b774b190cee989f2bdb73240a4ceb571187bbcab15cb8a4ad2d7b516b' 
  AND token = 'Ua1FJIB18g4lhQpy7YE4kBEAIBbEHIxZwSoWZ0TtCkc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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