SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'a566b5da7f2ee4a7be4bb2c17506afc51680422800abc111083445ade52de198' 
  AND token = 'Xv37WPtcWhZ0StmVS1I+BHIL+4BfdIkV2GGv/79Nq94=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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