SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '3fb51a8043db83e3a51a004231b64e77a8d0e28131d527a34509f0785e4f79a9' 
  AND token = '/2blSlSp/LLJLFgeUzjCsLRHbV3Q/J2WhvFbKQbyv/U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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