SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4b409a7862934f8e021fb4d98ec3b1ad53362e83c5c2657d3223b992947a1fa' 
  AND token = '0ilOGETzHo9veJKiARQT2NdplWF23fKADBgKSSYnkLo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}