SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3d8893857216921a900cf9dad948756318bfc4c578fa98bbdd28ca7a92634ec' 
  AND token = 'TanbzuuNN/YVfv+vbOpzwZGpA8Le8lIbmrJyBqpfoWs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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