SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6db5af86e4137e536db6c3ec97832a6beec769072779de8aac7d0b2bc9e2a22f' 
  AND token = 'Bxm9sy+BLrzYqXBmWJxmA/CPjB53h6OfEXpLawEgQeI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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