SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '434674386c979f6dd1c6abed5165c39eb5b44c30f61312be068dfd479b9b82bd' 
  AND token = '+Arx+06XLVPB2FC2veq2ynlKKyimHFKfUEfQrNBbrBE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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