SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b779b26d18bedab526f32761b9ea93ad187300c20a604d3257b601c9784c4504' 
  AND token = 'f86IRfGwpRatKPA/WyOwrHYpW+PjWTJvTx15G0ynJvw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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