SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3fd6fa75618d3f48965f99fc5425afc7659875fdc09113c53136bc9df2eb29e3' 
  AND token = 'lm98mMdmSTOWxIBN9CsyGCZUjARMmJMFlEDd1VcyaUs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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