SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e903df8be3c4a5592092b5feaaf6a884e107e5e60a8a448e7817ba18fef94fd2' 
  AND token = 'B/VVzGuoLDtVSJuxaQDXcOgi9vNWcY6mBSGQqLoxWko=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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