SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '40c1b82bbd445b78f73819ffdfc24e8869992ef703a42f4da110270f79f8d5e7' 
  AND token = 't87wG8WC+VEpJuN8BaLnpvKbKNDbtVPXghp/tF9c6MA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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