SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c774331e1eb2b9cb47b485a4f364699287a51306a1154a33baad1c3033350cae' 
  AND token = 'bip/nJBkR+UeM9NEPdmluA6bVwCt6eVPSEmrivnnUJ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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