SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4066ba78102a012b3482cdd90ac6324b291d81b8b951637ad550f6e3ee9af82' 
  AND token = 'MKvV952JGdzkG6msVBUNTiWrjmVj+j7bPA66JGf/ULE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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