SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3e52b5986d3ca1ee330c1611022a282f5b6c06173a6c87deee656df52941d45' 
  AND token = 'PtXacMXpsQp3pcDVPrzRuLJaa4jYXEykJkNB2dPI6XQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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