SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6efcc796929b88dc67ce3e3fa38ba2dbb6b71808c8743d3df1c2a0b8569c51b1' 
  AND token = 'So/1UipyZrJO4NIxcJQmlu2sWAtFErTbVmHc2sueebc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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