SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '8d073963de6bdf630e360404362fc15fee5702903a82ca934af05127719aa36c' 
  AND token = 'nR0kdLMfL5g6NXJ0ulB1O3D/qibGrI1CHPXK7UGDnUg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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