SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '76dcecfc36620936f1f2ad37a1664ed4baf6a00d25fa69824130e0422f0972a4' 
  AND token = '9kEBIBg/GU7tL+DmLvzLhYDdfYkJ/6RebOQjERrl4AM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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