SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a6686304337fb15e7d939c969165cb0fa09deb99128d940b493fe89b332e723' 
  AND token = 'oq6RGVnTCCrSFLDYVYSc+OLPKHw+KjXundajjx3Hohw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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