SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b29622440092d8fa6d16a10fc981f0a5d66ce00999bd01285c0d2fe029dc44a0' 
  AND token = 'blydUSjY+VxkOXK737VidxgjeH996wUtFfUJ3T5Jpzg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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