SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e671b643ec705716c51ccabcc9c98cdf582b5ebcf57887f40eed5afec3735a6d' 
  AND token = 'W6hn4FHT+aILmH5+adTvhVUCxh+KWDHpoCckXYFdQik=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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