SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1d3ff8f9b0f8f91c2e99793e694eddd7062055426c84802f4dd950a505f0f1dc' 
  AND token = 'VXkGNwFIRZUUqvJmWIpG7uxLDRzrFDr5Q+4i3tKMhrk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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