SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c2fdfb930bbfd9941ed9260cce2e72a7dbeb0d46c51c24ca3225cbfb387a3331' 
  AND token = 'ShbV4sMvOooD4LFGHNJGT8qoOMHt1GgJLejqzrFXqIQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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